Ignition distributors



- A ril 28, 1970, W, L, FRY 3,509,294

IGNITION DISTRIBUTORS Filed 00%- 25, 1967 F IGS.

INVENT BYmn-SM ATTORNEYS Mm i v United States Patent 3,509,294 1 IGNITION DISTRIBUTORS William Lawrence Fry, Kings Norton, Birmingham, England, assignor to Joseph Lucas (Industries) Limited, Birmingham, England Filed Oct. 25, 1967, Ser. No. 678,167 Claims priority, application Great Britain, Oct. 28, 1966, 48,428/ 66 Int. Cl. H01h 19/62 US. Cl. 200-22 11 Claims ABSTRACT OF THE DISCLOSURE An ignition distributor for a road vehicle includes a casing, a cam shaft mounted for rotation within the casing, and a contact breaker assembly supported by the casing. The contact breaker assembly includes a fixed contact, and the movable contact is carried by an insulating heel which is pivotally engaged with a pivot post of the contact breaker assembly. The insulating heel includes a pair of curved resilient arms which define between them a hole for receiving the pivot post, the arms being flexed outwardly when the heel is engaged with the pivot post so that by virtue of their own resilience, the arms grip the pivot post. The heel further includes a convex bearing surface which is engaged in use 'by the cam shaft of the distributor.

This invention relates to ignition distributors, for road vehicles, of the kind comprising, a casing, a cam shaft mounted for rotation within the casing and carrying the rotor arm of the distributor, a first plate within the casing and supporting a contact breaker assembly the assembly including a second plate, a pivot post upstanding with respect to said second plate, an insulating heel pivotally engaged with said pivot post, a contact carried by said heel, and movable therewith and a fixed contact carried by said second plate, the heel including a part which is engaged by said cam and moved in response to rotation thereof to open and close the contacts, the second plate being angularly movable with respect to said shaft to adjust the gap between the contacts.

According to one aspect of the invention in an ignition distributor of the kind specified said heel includes a pair of curved resilient arms defining a hole, the arms being flexed outwardly so that by virtue of their resilience they grip the post.

According to a second aspect of the invention in an ignition distributor of the kind specified the part of the heel which is engaged by the cam is convex.

The invention further resides in a contact breaker assembly for use in an ignition distributor, and in a heel for use in the contact breaker assembly of an ignition distributor.

One example of the invention is illustrated in the accompanying drawings wherein FIGURE 1 is a sectional view of an ignition distributor, FIGURE 2 is an inverted plan view of part of the contact breaker assembly shown in FIGURE 1 but to an enlarged scale and FIGURE 3 is a view in the direction of arrow A in FIGURE 1.

Referring first to FIGURE 1 the ignition distributor includes a casing 11 having secured therein an annular base plaate 12. Extending axially within the casing 11 and journalled for rotation therein is a cam shaft 13 including cam portion 13a and carrying at its upper free end the rotor arm (not shown) of the distributor.

Supported on the plate 12 for angular movement about the rotational axis of the shaft 13 is a timing plate 15 of a contact breaker assembly 14, the plate 15 being movable angnlarly relative to the shaft 13 by known means to vary the ignition timing of the distributor. Pivotally engaged with the plate 15 is an angle plate 16 including an integral upstruck tag 17 carrying the fixed contact 18 of the assembly. The plate 16 is movable angularly relative to the plate 15 to adjust the operating gap of the contacts of the contact-breaker assembly in known manner, there being provided a locking screw for clamping the plate 16 relative to the plate 15.

The assembly 14 further inclludes a moulded synthetic resin contact breaker heel 19 having integral therewith a cam follower 21 which in use engages the cam 13a to operate the contact breaker assembly. The heel 19 is provided at one end with a pair of substantially semicircular resilient arms 22 which define a hole 23. The wall of the hole 23 includes three substantially equiangularly spaced flat portions 24.

Extending around three faces of the heel 19 and secured by a rivet 26 is a U-shaped conductive strap 25. The heel 19 includes a first shoulder 27 defined at the junction of the cam follower 21 and the heel 19 and a second shoulder 27a defined at the junction of the arm 22, on the side of the heel 19 remote from the cam follower 21 and the heel 19, the strap 25 being located by the shoulders 27, 27a during manufacture of the assembly. The strap 25 includes an integral projection which extends beyond the heel 19 and carries the movable co tact 29 of the assembly.

In use the heel 19 is engaged with a pivot post 31 which extends from the plate 16, the axis of the post 31 and the axis about the plate 16 can pivot relative to the' plate 15 being coextensive. The post 31 has a diameter slightly larger than that of the hole 23 so that when the heel 19 is engaged with the post 31 the arms 22 are flexed outwardly and by virtue of their resilience to grip the post 31. The heel 19 makes contact with the post 31 at three portions 24 only, arcuate gaps 24a being formed between the three points of contact. In use the gaps 24a act as grease reservoirs, and the free end of the post 31 is spread to prevent disengagement of the heel 19 from the post 31.

The cam follower 21 includes a bearing face 32 which engages the cam 13a. In the past the face 32 has been flat so as to give the maximum bearing surface and correspondingly the lowest wear rate. However it is not uncommon for the cam follower to be misaligned with respect to the cam so that only a corner of the follower engages the cam resulting in undesirable high wear rate. The cam follower 21 shown in the drawings isprovided with a convex bearing face 32 so that in use the surface of the cam 13a will be tangential to the face 32 even if the follower 21 and the cam 13a are misaligned. Thefollower 21 will then wear at a substantial uniform rate irrespective of the point on the face 32 which engages the cam.

The lower surface of the heel 19 is formed with an integral projection 33 at the side of the hole 23 remote from the free ends of the arm 22. The projection 33 serves to support the heel 19 clear of the plate 16 is carried thereby insulating the strap 25, from the plate 16, and obviating the need for a separate insulating washer. It will be appreciated that a further pair of projections could be provided, the further projections being spaced around the hole 14 by from the projection 33.

The rivet 26 also serves to secure one end of a spring 34 to the heel 19, the spring 34 in use urging the heel 19 to a position wherein the movable contact 29 engages the fixed contact 18.

In a modification the arms 22 are part elliptical rather than part circular.

It will be appreciated that the invention is not limited to moulded heels and is equally applicable to heels formed in conventional materials, for example, certain of the Patented Apr. 28, 1970 class of materials sold under the registered trade mark Tufnol.

It will further be appreciated that the post 31 could be secured to the plate 15 rather than the plate 16, in which case the post 31 would extend through the plate 16 to receive the heel 19 and would not be spread to maintain the heel 19 engaged with the post 31 and furthermore the post 31 would constitute the pivotal connection between the plates 15, 16.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An ignition distributor comprising, a casing, a cam shaft, means mounting the cam shaft for rotation in the casing, a first plate, means mounting the first plate within the casing, a contact breaker assembly, means for mounting the contact breaker assembly on said first plate, the contact breaker assembly including a second plate, a pivot post upstanding with respect to the second plate, a fixed contact mounted on said second plate, an insulating heel, a movable contact mounted on the insulating heel, a cam follower part on said insulating heel and engageable by said cam shaft, and a pair of curved resilient arms on said insulating heel, said arms defining a hole through which said pivot post extends, and said arms being flexed to grip said post, said arms making contact with said pivot post at at least a pair of spaced points, and said arms mounting said heel for pivotal movement on said post, reservoirs capable of containing lubricant being defined by clearances between the arms and the pivot post in the regions between said contact points, and spring means urging said heel to pivot about said pivot post in a direction to engage said movable contact with said fixed contact, said cam follower part being engaged by the cam shaft as the cam shaft rotates so as to pivot said heel in a direction to disengage said movable contact from said fixed contact.

2. A distributor as claimed in claim 1 wherein said part on said insulating heel, which is engageable by said cam shaft, has a cam shaft engaging surface which extends in a direction parallel to the axis of the cam shaft, and which is convex with respect to the cam shaft, so that an axially extending surface of the cam shaft engages said cam engaging surface tangentially.

3. Adistributor as claimed in claim 1 wherein said arms are generally part circular and defined with the remainder of the heel, a hole of generally circular cross section.

4. A distributor as claimed in claim 1 wherein said arms are generally part elliptical and define with the remainder of the heel, a hole of generally elliptical cross section.

5. A distributor as claimed in claim 3 wherein the wall of the hole includes three circumferentially spaced fiat surfaces said post engaging the heel only at said fiat surfaces.

6. A distributor as claimed in claim 5 wherein the arcuate gaps defined by the post and the heel between the flat surfaces, act as lubricant reservoirs in use.

7. An ignition distributor comprising a casing, a cam shaft, means mounting the cam shaft for rotation in the casing, a first plate, means mounting the first plate within the casing, a contact breaker assembly, means mounting the contact breaker assembly on said first plate, the contact breaker assembly including a second plate, a pivot post upstanding with respect to the second plate, a fixed contact mounted on said second plate, an insulating heel, means pivotally mounting said heel on said pivot post, a movable contact mounted on said heel, the cam follower part on said heel engageable with the cam shaft, and spring means urging said heel to pivot about said pivot post in a direction to engage said movable contact with said fixed contact, and to engage said cam follower part with said cam shaft, said cam follower part having a cam shaft engaging surface which extendsin a direction parallel to the axis of the cam shaft and which is convex with respect to the cam shaft, so that an axially extending surface of the cam shaft engages said cam engaging surface tangentially.

8. A contact breaker assembly, for use in an ignition distributor, comprising a plate,'a pivot post, means mounting said pivot post on said plate, so that said pivot post is upstanding from said plate, an insulating heel, a pair of curved resilient arms on the insulating heel, said arms said post, a movable contact, means mounting the movdefining a hole through which said pivot post extends, so

3 that said arms pivotally mount the insulating heel on able contact on said insulating heel, a fixed contact, means mounting the fixed contact on said plate, and spring means, said spring means urging said insulating heel to pivot about said pivot post in a direction to engage said movable contact with said fixed contact, said curved re-' silient arms being flexed so as to grip said pivot post, and said arms making contact with said pivot post at at least a pair of spaced points, reservoirs capable of containing lubricant being defined by clearance between the arms and the pivot post in the regions between said contact points.

9. A contact breaker assembly as claimed in claim 8 wherein the hole defined "by said curved resilient arms is of generally circular cross-section, and the wall of the hole includes three circumferentially spaced flat surfaces, said pivot post engaging the heel only at said three flat surfaces.

10. A contact breaker assembly as claimed in claim 8 wherein said insulating heel further includes a cam follower part, said cam follower part having a cam engaging surface which extends in a direction parallel to the axis of rotation of the cam of the distributor in which the contact breaker is to be used, said cam engaging surface being convex with respect to said axis of rotation, so that an axially extending surface of the cam of the distributor will engage said cam engaging surface tangentially.

11. A contact breaker assembly, for use in an ignition distributor, comprising a plate, a pivot post, means mounting said pivot post on said plate, so that said pivot post is upstanding from said plate, an insulating heel, means mounting said insulating heel for pivotal movement on said pivot post, a movable contact, means mounting said movable contact on said insulating heel, a fixed contact, means mounting said fixed contact on said plate, spring means, said spring means urging said insulating heel to pivot about said pivot post in a direction to engage said movable contact with said fixed contact, and a cam follower part on said insulating heel, said cam follower part having a cam engaging surface which extends in a direction parallel to the axis of rotation of the cam of the distributor in which the contact breaker assembly is used, and which is convex with respect to said axis, so that an axially extending surface of the cam will engage said cam engaging surface tangentially.

References Cited UNITED STATES PATENTS 10/ 1961 .Meyer et al. 200-19 XR FOREIGN PATENTS 12/ 1947 Great Britain. 10/ 1960 Italy.

US. Cl. X.R. 

